The present invention is concerned with flat panel displays and particular liquid crystal displays (LCDs). More especially, the present invention relates to cover plates and/or back plates suitable for use in flat panel displays. In particular, the present invention is directed to the use of certain polymer compositions as the black matrix polymer layer of the plate. The polymer compositions employed in the present invention make it possible to lower the film thickness of the black matrix polymer layer without compromising the optical density. The present invention also relates to polymeric compositions. In addition, the present invention relates to liquid crystal displays employing the cover and/or back plates of the present invention.
Plates for liquid crystal display structures include a flat glass plate having a black matrix layer in a grid or mesh pattern located thereon. The mesh or grid pattern in the case of a cover plate is typically filled with an optical diffusion layer in the form of a translucent coating. Laminated onto the structure is a polarizer. To fabricate a liquid crystal display, liquid crystal panel or tile(s) are adhesively bonded to the cover plate and back plate.
A current method for fabricating the black matrix glass plate for various LCDs comprises the screening of a photosensitive dielectric on a flat glass plate about 1.1 mm thick and subsequent imaging the grid pattern using a photomask. Typical thicknesses of the dielectric used are 35-50 microns. The next step in the case of a cover plate involves coating and filling the pattern with the diffuser (a translucent coating). Following this, a polarizer is laminated onto the structure such as by rolling or autoclaving.
However, entrapment of air bubbles has been observed during this process. Air pockets provide areas for subsequent delamination, scattering of light and reliability concerns. As the size of the liquid crystal display increases, this problem becomes more pronounced.
Accordingly, these structures could withstand improvement.
The present invention addresses problems discussed above. In particular, the present invention provides a high contrast ink composition and makes it possible to obtain cover and/or back plate with a planar dark matrix structure free from entrapped air.
Compositions of the present invention exhibit increased opacity. This makes it possible to achieve the same optical density but at significantly thinner coatings.
In particular, the present invention relates to a plate comprising:
a transparent substrate;
a dark mesh material on the substrate having a thickness of about 1 to about 30 microns;
wherein the dark mesh material comprises a photocured photoimageable organic polymeric composition and about 0.01 to about 6 percent by weight of a coloring agent selected from the group consisting of organic dyes, organic pigments and inorganic dyes based upon the total of the polymeric composition and coloring agent; and wherein the dark mesh material has an optical density of about 0.5 to about 3 in the visible light range; and
a polarizing layer.
Another aspect of the present invention relates to a method for fabricating a plate structure. The method comprises applying a photoimageable composition to a transparent substrate at a thickness of about 1 to about 30 microns wherein the photoimageable composition comprises an organic polymeric composition and about 0.01 to about 6 percent by weight of a coloring agent selected from the group consisting of organic dyes, organic pigments and inorganic dyes based upon the total of the polymeric composition and coloring agent; and wherein the composition has an optical density of about 0.5 to about 3 in the visible light range;
exposing the composition to actinic radiation and developing to provide a mesh structure; and
placing a polarizer on the structure.
The present invention also relates to a liquid crystal display which comprises at least one liquid crystal display tile bonded to the above disclosed plate of the present invention.
The present invention also relates to preferred compositions employed according to the present invention. The preferred compositions comprise a photosensitive liquid epoxy acrylate; hardener; and about 0.01 to about 6 percent by weight of an organic black pigment-metal complex.
Still other objects and advantages of the present invention will become readily apparent by those skilled in the art from the following detailed description, wherein it is shown and described preferred embodiments of the invention, simply by way of illustration of the best mode contemplated of carrying out the invention. As will be realized the invention is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, without departing from the invention. Accordingly, the description is to be regarded as illustrative in nature and not as restrictive.